Muwatta Malik 31
Maqtu Sahih Graded by Salim al-Hilali Book of The Times of Prayer · Hadith 31 of 1,858وَحَدَّثَنِي عَنْ مَالِكٍ، عَنْ عَبْدِ الرَّحْمَنِ بْنِ الْمُجَبَّرِ، أَنَّهُ كَانَ يَرَى سَالِمَ بْنَ عَبْدِ اللَّهِ إِذَا رَأَى الإِنْسَانَ يُغَطِّي فَاهُ وَهُوَ يُصَلِّي جَبَذَ الثَّوْبَ عَنْ فِيهِ جَبْذًا شَدِيدًا حَتَّى يَنْزِعَهُ عَنْ فِيهِ .
Yahya related to me from Malik from Abd ar-Rahman ibn al-Mujabbar that he used to see Salim ibn Abdullah pull the cloth away fiercely from the mouth of any man he saw covering his mouth while praying
References
Muwatta Malik 31
In-book: Book 1, Hadith 31 Source: hadith-api (fawazahmed0)